Process for conditioning wringer rolls which treat one-side-coated sheet material



p 6, 1966 R. J. CHEN ETAL 3,271,137

PROCESS FOR CONDITIONING WRINGER ROLL HIGH TREAT ONE-SIDECOATED SHEET MATERI led 1965 Fi May 17,

. INVENTORS BY MUM M MW ATTORNEYS 3,271,187 PROCESS FOR QONDHTIONING WRHNGER ROLLS WHICH TREAT ONE-SIDE-CUATED SHEET MA- TERIAL Richard .1. Chen, Broclrtou, and Nicholas Gold, Arlington, Mass, assignors to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Filed May 17, 1965, Ser. No. 456,417 3 Claims. (Cl. 117102) A number of processes, particularly photographic processes, involve the application of an accurately predetermined quantity of a liquid-processing agent to one side of each of a succession of sheets. For example, in the process and apparatus disclosed in copending US. application, Serial No. 456,422, filed May 17, 1965, in the name of Edwin H. Land et al., entitled Photographic Process and Apparatus for Producing Photographic Images, a succession of photosensitive sheets are treated with a predetermined quantity of a liquid-processing agent by applying excess liquid to one side of each sheet, permitting a predetermined quantity of the liquid to be absorbed into the sheet and then advancing the sheet between a pair of wringer rolls to remove excess liquid from the sheet. The liquid is applied to one side of each successive sheet without contacting the opposite side of the sheet by moving each sheet against an applicator roll. However, excess liquid removed from each sheet collects and remains as a meniscus at the nip of the wringer rolls where, if allowed to remain, it will wet the surface of the roll which contacts the dry sides of the sheets, may evaporate leaving a residue on the wringer rolls and, of course, will wet both sides of the succeeding sheet. All of these possibilities are particularly undesirable in a photographic process of the type described in the aforementioned application in which the liquid is highly corrosive, deteriorates on exposure to the atmosphere and is subject to contamination by the residue thereof, and the wet sides of the sheets are so constituted as to be easily marred, particularly when wet.

Objects of the invention are: to provide novel and improved processes for removing liquid from one side of each of a succession of sheets without Wetting the opposite sides thereof by means for removing liquid from the nip of a pair of wringer rolls immediately as the trailing edge of the sheet from which the liquid is removed passes between the rolls.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the ac companying drawing wherein:

FIGURE 1 is an elevational, sectional view showing the apparatus and process of the invention;

FIG. 2 is a fragmentary sectional View similar to FIG- URE 1 showing a portion of the apparatus thereof; and

FIG. 3 is a fragmentary sectional view similar to FIG- URE 1 illustrating in detail the construction and operation of the apparatus.

The apparatus incorporating the invention and illustrated in the drawing generally comprises means for applying a liquid to one side of each of a succession of sheets, allowing the liquid to be absorbed into each sheet for a predetermined period, removing excess liquid from dflllhlii'i Patented Sept. 6, 1966 the surface of each sheet, and disposing of the excess liquid so that it does not remain on the means for removing the excess liquid and come into contact with the dry surface of the next succeeding sheet. The liquid applicator means, in the form shown, comprise a generally cylindrical applicator roll 1'9 mounted for rotation about an axis disposed in a generally horizontal plane with the lower portion of the peripheral surface of the roll disposed within a recess or cavity 12 formed in the upper side of a member 14. Recess 12 is at least equal in length to roll 11! and the sides of the recess are defined by walls inclined inwardly toward the center of the recess. A second cavity or recess 16 is provided in member 14 beneath cavity 12 and opening into the last-mentioned cavity. A closure member or valve 18 is mounted within cavities 12 and 16 and includes an upper section having edge portions 20 for engaging the walls of recess 12 adjacent the periphery of second cavity 16 to prevent the flow of liquid from cavity 12 into second cavity 16. Suitable means (not shown) are provided for introducing a quantity of a processing liquid, designated 22, into cavity 12 in contact with the peripheral surface of roll 10 so that the surface of the roll will become coated with and carry the liquid upwardly as the applicator roll is rotated.

As previously noted, the liquid may be of the type which decomposes upon exposure to the atmosphere and is contaminated by its own residue so that the applicator means shown include provision for withdrawing excess liquid from cavity 12 following application of the liquid to each successive sheet and removing liquid from the surface of roll 10 so that the liquid does not remain thereon allowing a dried residue to collect. For this purpose, closure member 18 is mounted on a shaft 24 engaged in a slot in member 18 and extending axially from a second shaft 26 mounted for rotation about its axis in member 14. Shaft 26 extends through member 14 into recess 16 and shaft 24 is mounted with its axis out of alignment with the axis of shaft 2o so that rotation of shaft 26 is effective to move closure member 18 between a lower or closed position shown in FIGURE 1 and a raised or open position shown in FIG. 2. The upper surface 28 of closure member 18 is concave and shaped to conform to the peripheral surface of applicator roll 10 and in the raised position of the closure member, the applicator roll displaces the liquid from between the applicator roll and closure member. Following coating of a sheet, the applicator roll is rotated through at least one complete revolution during which the edge of one of portions 211 of closure member 18 removes any liquid on the peripheral surface of the applicator roll. Upper surface 28 of the closure member may be covered with a layer of a material such as polytetrafiuoroethylene, which is durable, is unaffected by many liquids, particularly aqueous liquids, and has a low coefiicient of friction. Second cavity 16 may be coupled with means for reducing the pressure within the second cavity and thereby removing liquid which flows from cavity 12 into the second cavity.

Liquid is applied by roll 10 to a sheet, designated 30, for advancing the sheet with the surface (lower) to be coated in contact with an upper portion of the periphenal surface of roll 10, preferably in a direction such that the surface of the roll is moving oppositely to the sheet. Sheet 30 is supported against the roll and moved relative to the roll by a backing roll 32 mounted for rotation above applicator roll 10 about an axis located parallel with the axis of the applicator roll. Backing roll 32 is provided with a plurality of knife-edge cylindrical collars 34 which engage and advance successive sheets 30 while limiting the area of contact between the backing roll and applicator roll 10, thereby reducing friction between the rolls and substantially eliminating the possibil-i-ty of the backing roll becoming coated with the processing liquid and transferring it to the upper surf-aces of the sheets. Suitable means are provided for rotating the applicator and backing rolls in the same direction to apply the liquid to the lower surfaces of the sheets and advance the sheets in a direction opposite to the direction of movement of the peripheral surface of the applicator roll.

The means for removing excess liquid from the lower surfaces of successive sheets comprise an upper wringer roll 36 and the lower wringer roll 38. The wringer rolls are substantially cylindrical and are mounted in juxtaposition for rotation about substantially parallel axes with the nip of the wringer rolls disposed a predetermined distance from the nip of the applicator and backing rolls. The quantity of liquid absorbed by each sheet 30, is, of course, a function of the distance between the applicator roll and the nip of the wringer rolls and the speed of movement of each sheet through this distance, and can be predetermined with a fair degree of accuracy. The wringer rolls are preferably formed with the surface portions composed of a material having at least some pliability, for example, an elastomer such as rubber, and the peripheral surface of at least roll 38 is substantially smooth so as to insure against marring of the lower surfaces of sheets 30. The apparatus includes means in the form of wires 40 mounted above and below the path of movement of sheets 30 from the applicator roll to the nip of the wringer rolls and disposed in the direction of movement of the sheets for guiding the sheets from the applicator roll into the nip of the wringer rolls. Wires 40 are employed as guides in order to limit the area of contact between the sheets and the guides.

Wringer rolls 36 and 38 are biased toward one another so as to engage and compress each successive sheet 30 and remove from the lower surface of the sheet, liquid not absorbed into the sheet. This liquid tends to collect as a meniscus 42 between sheet 30 and the peripheral surface of roll 38 at the nip of the wringer rolls and remains at the nip of the rolls as the trailing edge of each sheet 30 passes between the rolls. If provision were not made for removing the liquid comprising meniscus 42, the liquid would contact roll 36 Wetting the peripheral surface thereof and remain in the nip of the rolls until it either evaporated, possibly leaving a deleterious residue, and/ or came into contact with and be deposited upon the surfaces, particularly the upper surface, of the next succeeding sheet 30.

The invention contemplates means for removing the excess liquid comprising meniscus 42 from the nip of the rolls substantially immediately as the trailing edge of a sheet 30 passes between the wringer rolls, while substantially preventing the liquid from coming into contact with the peripheral surface of roll 36. These means comprise an endless, perforated web or screen 44, preferably having smooth surfaces and shown as a cylinder engaged around roll 36 disposed so as to pass between roll 36 and the upper surfaces of sheets 30. Web 44 is preferably formed of a material such as sheet metal, having sufiicient rigidity to retain its cylindrical shape and includes a plurality of minute openings 46 for entrapping and entraining the liquid comprising meniscus 42. Web 44 is approximately equal in width to the lengths of the wringer rolls and the cylinder formed thereby has an internal diameter substantially greater than the outer diameter of wringer roll 36 around which the web is engaged. As a non-limiting example, a stainless steel 250 wire mesh screen formed into a three inch diameter tube and engaged around a one inch diameter wringer roll proved satisfactory for removing the liquid from the nip of the wringer rolls of photographic apparatus employed in the process described in the aforementioned copending application.

For expelling liquid entrained in openings 46 during rotation of the wringer rolls, the apparatus includes means providing a first chamber 43 located within the cylinder comprising web 44 and extending closely adjacent and from side to side of the web, and means for introducing air under pressure into chamber 48 to force the air through openings 46 in the web and expel the liquid from the openings; and a second chamber 50 located on the opposite side of the web in juxtaposition with the first chamber and means for reducing the pressure within second chamber 50 for withdrawing the liquid from the openings in the web and from chamber 50 which also functions to collect liquid expelled from the openings by air passage there-through from chamber 48. Expelling the liquid from the openings in the web by passing a gas through the openings is the preferred method for removing liquid entrained in the web because it contributes materially to insuring removal of all the liquid before the liquid has an opportunity to evaporate and leave a residue of reagents dissolved in the liquid; and it is for this reason that chambers 48 and 50 are preferably located as close as possible to the nip of the rolls. Suitable means such as internal ribs or collars 52 are provided secured to the edges of web 44 for adding structural strength and rigidity to the web and disposed in engagement with the ends of upper wringer roll 36 for guiding the web between the wringer rolls and retaining it in proper axial relationship to the wringer rolls. The apparatus may include suitable means near the ends of chamber 49 and 50 for engaging and guiding web 44 during movement thereof between the chambers.

Since certain changes may be made in the above apparatus and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A method of treating one side of each of a succession of sheets with a liquid without wetting the opposite sides of said sheets comprising:

applying a liquid to one side of each of a succession of sheets for adsorption into said each sheet; allowing a portion of said liquid to be absorbed into said each sheet;

removing excess liquid from said one side of said each sheet by moving said one side of said each sheet relative to a pressure roll while pressing said one side of said sheet against said pressure roll by pressing a perforated strip against the opposite side of the sheet and collect-ing liquid removed from said each sheet between said one side thereof and said pressure roll;

immediately following movement of said each sheet from contact with said pressure roll and prior to movement of the next succeeding sheet into contact with said pressure roll, removing from said pressure roll said liquid collected thereon by rotating said pressure roll against said perforated strip to entrap said liquid in the perforations in said strip; and expelling said liquid from said perforations.

The method of claim '1 wherein said liquid is expelled from said perforations by passing a gas through said perforations.

3. The method of claim 1 wherein said liquid is expelled from said perforations by propelling a gas against a region of one side of said strip while simultaneously reducing the pressure on the opposite side of said strip in a region thereof aligned and coextensive with the firstmentioned region.

(References on following page) 5 6 References Cited by the Examiner 2,246,531 6/1941 Novak 11'81 17 2,772,606 12/ 1956 Kelly 162276 UNITED STATES PATENTS 2,843,505 7/ 1958 'Riedel 1185 6 X 464,467 12/1891 Tucker 162-476 2,852,986 9/:1958 Western et .al. 162263 948,012 2/ 1910 Goldsmith 118102 5 1,759,600 5/ 1930 Wilshier 118-117 X FOREIGN PATENTS 1,933,837 1 1/1933 ATIlOld 1 18104 377 440 1923 Germany 2,094,348 9/ 1-937 Carlson. 2,209,760 7/1940 Berry 100162 X MORR-IS KAPLAN, Primary Examiner. 

1. A METHOD OF TREATING ONE SIDE OF EACH OF A SUCCESSION OF SHEETS WITH A LIQUID WITHOUT WETTING THE OPPOSITE SIDES OF SAID SHEETS COMPRISING: APPLYING A LIQUID TO ONE SIDE OF EACH OF A SUCCESSION OF SHEETS FOR ADSORPTION INTO SAID EACH SHEET; ALLOWING A PORTION OF SAID LIQUID TO BE ABSORBED INTO SAID EACH SHEET; REMOVING EXCESS LIQUID FROM SAID ONE SIDE OF SAID EACH SHEET BY MOVING SAID ONE SIDE OF SAID EACH SHEET RELATIVE TO A PRESSURE ROLL WHILE PRESSING SAID ONE SIDE OF SAID SHEET AGAINST SAID PRESSURE ROLL BY PRESSING A PERFORATED STRIP AGAINST THE OPPOSITE SIDE OF THE SHEET AND COLLECTING LIQUID REMOVED FROM SAID EACH SHEET BETWEEN SAID ONE SIDE THEREOF AND SAID PRESSURE ROLL; IMMEDIATELY FOLLOWING MOVEMENT OF SAID EACH SHEET FROM CONTACT WITH SAID PRESSURE ROLL AND PRIOR TO MOVEMENT OF THE NEXT SUCCEEDING SHEET INTO CONTACT WITH SAID PRESSURE ROLL, REMOVING FROM SAID PRESSURE ROLL SAID LIQUID COLLECED THEREON BY ROTATING SAID PRESSURE ROLL AGAINST SAID PERFORATED STRIP TO ENTRAP SAID LIQUID IN THE PERFORATIONS IN SAID STRIP; AND EXPELLING SAID LIQUID FROM SAID PERFORATIONS. 